Good evening! I'm hoping some of the more seasoned LEGO train fans here can help me with a problem. I have built 2 Santa Fe F7 Units. I have put a PF rechargeable battery box in the rear section, a PF receiver in the front section and a PF power truck underneath the battery (from the Red Passenger Train that is still for sale on LEGO.com). The engine runs fine buy itself, but as soon as I add the 2nd dummy F7 or any cars, the power truck just sits and spins.

What would be the best way to power this loco? I tried adding a second power truck to the front of the loco, but it runs in the opposite direction of the first one. Any ideas? Thank you all in advance!

It's good to hear there are more Lego train builders around here. If there are any pictures of these locomotives online, that might be helpful. Without knowing anything else, though, I imagine a second motor would help a lot. Just turn one around relative to the other so they're spinning the same way.

If you don't want to do that, it's possible there is a problem with weight distribution or some issue with parts binding on each other behind this. If the engines you built were 6-wide and a similar scale to the Lego Super Chief set, I would think one motor would be more than enough. I think we'd need to see it to figure out anything else, though.

Hello Ron I have just powered my sante fe with power functions it has a traction problem a fellow member Joel (Evil Jack) added some of the boat weight bricks to it and it pulled ok also the train god Cale Leipert also told me the old grey wheel sets are very prone to binding and need to be fixed to free up the traction problem maybe cale can post a link to the fix or something for you I used just one power truck and it pulled an F7-A-B-and the 4 cars in the sante fe set it ran for 4+ hours on a set of batterys Hope this helps I did power the B-UNIT not the A Tony E

Thank you guys for the advice. I'm setting up a BrickShelf account so I can upload some photos for everyone to see of this project. The build is the 6 wide Santa Fe F unit done some time ago. Since I only have plastic track, I need to make it compatible with PF. I could use 2 power trucks, but unlike the old 9V power trucks that you just snapped in, I have the wiring back to the PF Receiver to worry about. Just truning the truck around so that the wires are facing the same direction doesn't seem to be an option, since the only holes in the train baseplate for the wires are in the center. Is there a way to reverse the polarization of one of the trucks?

The other option I was considering is 2 geared Technic trucks with shafts into the carbody, then using 2 PF motors to power them. Only problem with that is the PF motors are taller than the carbody.

I just can't believe a single PF Power Truck cannot pull the engine itself and a dummy engine. Would putting better rubber bands on the wheels help?

It's just a matter of wiring to get them running in same direction just flip the way you have the wire connected to the power source. This is assing you have both motor going to the same IR sensor. If your using two different sensors then you need to flip the directional switch on the controller you are using.

And as Tony said its a traction issue. There is plenty of power in the new motor you just have to make it stick to the track. Easiest solution is more weight. Better rubber on the wheels will help as well.

Well, looking at that, there are a couple things you might try. There's no reason a new PF motor couldn't pull that and a few cars. Adding weight might help if there's room to do it. Also, you might try some thicker rubber on the wheels. We usually use plumbing o-rings. Get the thinner ones: they'll still be quite a bit thicker than the stock Lego rubber. Here's a Railbricks post about it from Tony Sava where he suggests the #35 o-rings:

Hello again! Thank you all for the fine suggestion on motorizing my F7 with power functions. Turns out the problem was three-fold.

First of all, I replaced the rubber traction bands as suggested. Good improvement!Second, I added some extra weight above the power truck to improve the downward force and traction.Third and most importantly, I replaced the technic axles with the standard metal train wheel axles (with a little bit of shimming of course). This made the biggest difference by greatly reducing the wheel friction.

I will post some photos of my alterations when I get a little more time. Thank you again for all of your great ideas.

It's good to hear you've got your engine running better. The issue Tony mentioned with the older gray wheel sets is that due to improper molding the walls of the wheel holder surrounding the flanges of the wheels is too thick. This causes the holder to contact the wheel and cause excessive friction. Here is an illustration of what I'm talking about.

This was predominately a problem around the time the Super Chief sets were produced affected the grey wheel sets. I've never heard of much problem with the black wheel sets around this time. If you have the gray wheel sets and they are rubbing and you don't mind modifying your wheels they can be fixed. You'll need to take an exact o knife and carefully shave the inner part of the wheel set that rubs the flange.

My Super Chief set has this problem but I've never bothered to fix mine.

That's obviously not a LEGO Santa Fe engine. It must be clone brick the way it falls apart. A true LEGO train stays together better when it falls. I know this.

My response to you is the same as the one to those who say a cat always lands on its feet.

You are not thowing it right.

Tony Sties

Ha ha ha. The funniest part is that BNSF engine that I crashed belonged to some one else. Mine was the one still on the table. And of corse as soon as it hit the floor some one was there to get photographic evidence of the incident.